Laser Phase Interferometry is a measurement technique that uses the interference of laser beams to detect extremely small changes in distance, refractive index, or vibration. At NEC Labs America, laser phase interferometry is applied in distributed fiber sensing and high-sensitivity monitoring. The approach allows researchers to measure environmental changes at fine resolution, advancing applications in structural health monitoring, seismic detection, and precision metrology.

Posts

Advances in Fiber Sensing

In this talk, we will present recent technological advances in fiber sensing applications with long monitoring distances orextending multiple fiber spans. In forward-transmission-based sensing, adaptive beamforming techniques weredemonstrated to achieve multi-event vibration sensing in environments with interference and jamming with significantimprovements in signal reconstruction, noise reduction, and interference rejection from other locations. For sensing oversubmarine cables with many fiber spans with repeaters, it is shown that distributed reflection from Rayleigh scattering canbe detected with sufficient SNR for fiber sensing using HLLB paths. In particular, longitudinal averaging of receivedRayleigh scattered signals can facilitate state-of-polarization-based, multi-span sensing using eigenvalue method.

Strain Accumulation Rate in Fiber Spools in the Presence of Ambient Acoustic Noise in Laser Phase Interferometry

We investigate the growth rate of phase power spectral density in fiber spools in the presence of ambient acoustic noise, observing a complex interplay between spool geometry, shielding effects, and phase cancellation at high acoustic frequencies.